What is the equation in slope-intercept form for a line that passes through the points (-3, 6) and (9, 10)?

Responses
A
y = 1 x + 5
3
y = 1 x + 5 3
B
y = 1 x + 7
3
y = 1 x + 7 3
C y = 3x + 15y = 3 x + 15
D y = 3x – 3

1 answer

To find the equation of the line in slope-intercept form (y = mx + b) that passes through the points (-3, 6) and (9, 10), we first need to calculate the slope (m) using the slope formula:

\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]

Using the points (-3, 6) and (9, 10):

  • \(x_1 = -3\), \(y_1 = 6\)
  • \(x_2 = 9\), \(y_2 = 10\)

Substituting these values into the slope formula:

\[ m = \frac{10 - 6}{9 - (-3)} = \frac{4}{9 + 3} = \frac{4}{12} = \frac{1}{3} \]

Now, we have the slope \(m = \frac{1}{3}\).

Next, we use one of the points to solve for the y-intercept (b) using the slope-intercept form equation \(y = mx + b\). We can use the point (-3, 6):

\[ 6 = \frac{1}{3}(-3) + b \]

Calculating this gives:

\[ 6 = -1 + b \] \[ b = 6 + 1 = 7 \]

Now we have both the slope and y-intercept. The equation of the line is:

\[ y = \frac{1}{3}x + 7 \]

Thus, the answer is:

B: \(y = \frac{1}{3}x + 7\)